CATV networks use an infrastructure of interconnected coaxial cables, signal splitters and combiners, repeating amplifiers, filters, trunk lines, cable taps, drop lines and other signal-conducting devices to supply and distribute high frequency “downstream” signals from a main signal distribution facility, known as a “headend,” to the premises (homes and offices) of CATV subscribers. The downstream signals operate the subscriber equipment, such as television sets, telephone sets and computers. In addition, most CATV networks also transmit “upstream” signals from the subscriber equipment back to the headend of the CATV network. For example, the subscriber uses a set top box to select programs for display on the television set. As another example, two-way communication is essential when using a personal computer connected through the CATV infrastructure to the public Internet. As a further example, voice over Internet protocol (VOIP) telephone sets use the CATV infrastructure and the public Internet as the communication medium for two-way telephone conversations.
To permit simultaneous communication of upstream and downstream CATV signals, and to permit interoperability of the subscriber equipment and the equipment associated with the CATV network infrastructure outside of subscriber premises, the downstream and upstream signals are confined to two different frequency bands. The downstream frequency band is within the range of 54-1002 megahertz (MHz) and the upstream frequency band is within the range of 5-42 MHz, in most CATV networks.
The downstream signals are delivered from the CATV network infrastructure to the subscriber premises at a CATV entry adapter, which is also commonly referred to as an entry device, terminal adapter or a drop amplifier. The entry adapter is a multi-port device which connects at an entry port to a CATV drop cable from the CATV network infrastructure and which connects at a multiplicity of other distribution ports to coaxial cables which extend throughout the subscriber premises to cable outlets. Each cable outlet is available to be connected to subscriber equipment. Typically, most homes have coaxial cables extending to cable outlets in almost every room, because different types of subscriber equipment may be used in different rooms. For example, television sets, computers and telephone sets are commonly used in many different rooms of a home or office. The multiple distribution ports of the entry adapter deliver the downstream signals to each cable outlet and conduct the upstream signals from the subscriber equipment through the entry adapter to the drop cable of the CATV infrastructure.
In addition to television sets, computers and telephones, a relatively large number of other entertainment and multimedia devices are available for use in homes. For example, a digital video recorder (DVR) is used to record broadcast programming, still photography and moving pictures in a memory medium so that the content can be replayed on a display or television set at a later time selected by the user. As another example, computer games are also played at displays or on television sets. Such computer games may be those obtained over the Internet from the CATV network or from media played on play-back devices connected to displays or television sets. As a further example, signals from a receiver of satellite-broadcast signals may be distributed for viewing or listening throughout the home. These types of devices, including the more-conventional television sets, telephone sets and devices connected to the Internet by the CATV network, are generically referred to as multimedia devices.
The desire to use multimedia devices at multiple different locations within the home or subscriber premises has led to the creation of the Multimedia over Coax Alliance (MoCA). MoCA has developed specifications for products to create an in-home entertainment network for interconnecting presently-known and future multimedia devices. A MoCA in-home network uses the subscriber premise or in-home coaxial cable infrastructure originally established for distribution of CATV signals within the subscriber premises, principally because that coaxial cable infrastructure already exists in most homes and is capable of carrying much more information than is carried in the CATV frequency bands. A MoCA network is established by connecting MoCA-enabled or MoCA interface devices at the cable outlets in the rooms of the subscriber premises. These MoCA interface devices implement a MoCA communication protocol which encapsulates the signals normally used by the multimedia devices within MoCA signal packets and then communicates the MoCA signal packets between other MoCA interface devices connected at other cable outlets. The receiving MoCA interface device removes the encapsulated multimedia signals from the MoCA signal packets, and delivers the multimedia signals to the connected display, computer or other multimedia device from which the content is presented to the user.
Each MoCA-enabled device is capable of communicating with every other MoCA-enabled device in the in-home or subscriber premises MoCA network to deliver the multimedia content throughout the home or subscriber premises. The multimedia content that is available from one multimedia device can be displayed, played or otherwise used on a different MoCA enabled device at a different location within the home, thereby avoiding physically relocating the originating multimedia device from one location to another within the subscriber premises. The communication of multimedia content over the MoCA network is considered beneficial in more fully utilizing the multimedia devices present in modern homes.
Since the operation of the subscriber premises MoCA network must occur simultaneously with the operation of the CATV services, the MoCA signals utilize a frequency range different from the frequency ranges of the CATV upstream and downstream signals. The typical MoCA frequency band is 1125-1525 MHz.
In addition to traditional cable television service, a telephone service, known as “lifeline telephone service,” is also available to many CATV subscribers. Lifeline telephone service remains operative in emergency situations, even during a loss of power to the subscriber premises. An embedded multimedia terminal adapter (eMTA) device which includes a cable modem and a telephone adapter is used to receive the telephone service. The telephone service is typically implemented using a voice over Internet protocol (VOIP) communicated by the CATV upstream and downstream signals. Since the telephone service is expected to be available during a loss of power to the subscriber premises, CATV entry adapters adapted for use with an eMTA device have a passive port to which passive CATV upstream and downstream signals are conducted without amplification or other conditioning by an active electronic component. As a consequence, the loss of power at the subscriber premises does not adversely affect the communication of passive CATV signals to and from the passive port.
In addition to the passive port, CATV entry adapters typically have an active signal communication path which amplifies the CATV downstream signals and conducts them to a plurality of active ports of the CATV entry adapter. Subscriber equipment connected to the active ports typically benefits from the amplification of the CATV downstream signals. However, the loss of power to the entry adapter adversely influences the active signals conducted to and from the active ports through power-consuming components which become inoperative when power is lost. The communication of active CATV signals under power loss conditions is severely compromised or impossible.
Most eMTA devices used for passive CATV signal communication are not presently MoCA-enabled. However, MoCA-enabled eMTA devices are recognized as useful for expanding the number of multimedia devices in the MoCA network. For example, telephony multimedia devices such as auxiliary telephone sets and answering machines could interact with a MoCA-enabled eMTA device and provide telephony services throughout the subscriber premises. In order for multimedia devices to communicate with the MoCA-enabled eMTA device, the CATV entry adapter must be capable of communicating MoCA signals between the passive and active ports.
One technique to allow MoCA signal communication between the passive and active ports is to use a MoCA signal bypass path which contains a bandpass filter for MoCA signal frequencies, as is discussed in the above-referenced previous patent application. Such a MoCA signal bypass path is essentially parallel with an active signal communication path which communicates the active CATV upstream and downstream signals between the active ports and the CATV network. However, including the MoCA bandpass filter in the MoCA bypass path in parallel with the active CATV signal communication paths has an effect on the other parallel signal paths. The filters of each path cause changes in the frequency response characteristics of the other parallel path filters. As a result of these effects, additional and time-consuming tuning of the filters in the parallel signal communication paths is required to achieve the desired frequency response. In some cases, more extensive, complex and costly filters must be used in the parallel filter paths. The additional tuning and increased complexity of the filters increases the costs of the entry adapter. The requirement for precise tuning and the added complexity increases the risk of failure or the risk of deterioration in the quality of service experienced by the customer. Such risks also increase the frequency of service calls made by the CATV service provider, and such service calls are a significant expense to the service provider.